As the area around Stonehenge is among the world’s most-studied archaeological landscapes, the discovery is all the more unexpected. Having filled naturally over millennia, the shafts – although enormous – had been dismissed as natural sinkholes and dew ponds. The latest technology – including geophysical prospection, ground-penetrating radar and magnetometry – showed them as geophysical anomalies and revealed their true significance.
Gaffney said: “We are starting to see things we could never see through standard archaeology, things we could not imagine.”
Based at the University of Bradford, he is the co-principal investigator of the Stonehenge Hidden Landscape project, which has been surveying tens of kilometres of landscape across Salisbury Plain. Archaeologists are now joining the dots and seeing this massive pattern, he said. Coring of the shafts has provided crucial radiocarbon dates to more than 4,500 years ago, making the boundary contemporary with both Stonehenge and Durrington Walls.
The boundary also appears to have been laid out to include an earlier prehistoric monument, the Larkhill causewayed enclosure, built more than 1,500 years before the henge at Durrington.